Projectile



Nov. 9, 1965 w. F. KAUFMANN, JR 3,216,356

PROJECTILE Filed Jan. 50, 1964 Fig! I INVENTOR. f WILLIAM F. KAUFMANN,JR

: I EY- /W% W [M1 21 ATTORNEY- United States Patent ()filice 3,216,356Patented Nov. 9, 1965 3,216,356 PROJECTILE William F. Kaufmann, Jr.,Philadelphia, Pa., assignor to the United States of America asrepresented by the Secretary of the Army Filed Jan. 30, 1964, Ser. No.341,463 2 Claims. (Cl. 10238) (Granted under Title 35, US. Code (1952),sec. 266) The invention described herein may be manufactured and used byor for the Government for governmental purposes without the payment tome of any royalty thereon.

This invention relates to a caseless round such as is used in recoillessrifles and has for an object to provide an abutment or stop ring on aprojectile for limiting loading movement of such a round into a gun inthe absence of a base flange of the type found on customary metalcartridge cases. Another object is to provide such a stop ring capableof being sheared at a predetermined pressure such as propellant gas togive the projectile a shotstart effect with high acceleration and highermuzzle velocity.

Caseless rounds have long needed a satisfactory stop ring for accuratepositioning of the round in the chamber of a gun, especially thosehaving a firing pin for either percussion or electrically fired primerswhere moving the round too far into a gun may result in a misfire.Conversely, when a round is not moved far enough into a chamber there isdanger of the primer cap being ruptured with a resulting rearwardleakage of gas.

This invention has not only overcome these difficulties, but has enabledthe present round to have a higher than usual acceleration and velocity.Specifically, a somewhat elastic ring is secured to the projectile andis fitted within a groove rearwardly of the projectile rotating band toextend radially outward far enough for engaging an inwardly extendingledge within the chamber of the gun. This ring is preferably of aplastic having an ultimate shear strength of about 20,000 pounds persquare inch, so that on rupture of the ring, the projectile is givenmore rapid acceleration and velocity for a given propellant than itwould have had with a metal cartridge case having a conventional baseflange arrangement.

Referring to the drawing:

FIG. 1 is a longitudinal view partially broken away in section of acomplete round of ammunition embodying the principles of the invention.

FIG. 2 is a partial longitudinal section through a portion of theprojectile body containing the grooves for reception of the abut-mentring and the rotating band.

FIG. 3 is a view corresponding to FIG. 2 but showing the abutment ringand rotating band in place.

FIG. 4 shows apparatus employed for applying the stop ring to itsprojectile groove.

The projectile body shown in FIG. 1 is provided with a nose 11 carryingany well known type fuze initia tor for an explosive charge. A boom 12extends from the body 10 rearwardly and is provided at its rear end witha plurality of stabilizing fins 13. A frangible fiber glass case 14encloses a well known type of propellant 14a, both encompassing the boom12.

As shown in FIGS. 2 and 3 a rotating band 15 is secured within groove 18on a rear portion of the projectile body 10. Rearwardly of and spacedfrom the band 15 a groove 19 is provided for reception of an abutmentring 16. Screw threads 17 on a rear inner surface of the projectile body10 enable the threaded boom 12 to be secured firmly to the body 10. InFIG. 2 the grooves 18 and 19 each have an appropriate width and depthfor receiving the rotating band 15 and the abutment ring 16. The band 15and ring 16 each is formed of a polyvinyl chloride plastic known as Geonhaving an ultimate strength in shear of about 20,000 pounds per squareinch. The band 15 is sufiiciently deformable to be readily engraved bythe rifiing when a low spin rate of around 15 to 20 revolutions persecond is desired. In one size in which this invention was tested thediameter of the body portion of the projectile immediately in front andbehind the grooves 18 and 19 was 4.71 inches. The diameter of theradially outside surface of band 15 was 4.74 inches and that of the ring16 was 4.84 inches, thus the projection of band 15 was .015 inch andthat of the ring was .065 inch, making the ring project outwardly ofsurface 22a about 4 times the radial projection of the rotating band 15.

A short plug or mandrel 21 (FIG. 4) is slid into the rear open end ofthe body 10 when the boom 12 is disconnected from the projectile body 10so that the abutment ring 16 may be secured to the projectile. For thispurpose, expandable ring 16 is first pressed onto the tapered end 25 ofmandrel 21 and moved gradually upward onto the portion 22 which has thesame outside diameter as that of the body portion 22a immediately infront and in rear of the band 15 and ring 16. After mounting ring 16 onfixture or support 23 having three or more prongs equally angularlyspaced, the projectile is forced downwardly upon spring 24, resulting inthe ring 16 being moved upward along the mandrel outer surface. Bypressing downward slightly on the body 10, ring 16 will be further movedupward along flush members 22, 22a until ring 16 slips into groove 19.Its inherent elasticity holds ring 16 in place with-in groove 19. Sincethe rotating band 15 is of the same elastic material as ring 16 thatband may also be slid into its groove in an even more easy mannerbecause band 15 is relatively thinner and more easily stretched. Thebottom of groove is of a size to maintain band 15 under slight tensionand is also provided with fine knurling 20 to cause band 15 to dig intoor be partially embedded in such knurling and thus oppose any tendencyfor the band to be shifted angularly by the rifling.

The term consumable case or caseless round includes not only those caseswhich are consumed by breakage or frangibility but also those consumedby being burned or consumed in any other manner as well as those withoutany case.

The reason the ring 16 and band 15 are separated is because at firstthey were made structurally integral, but such was found unsuitablebecause of an objectionable tilting of the unit. However theirseparation in the manner shown has proven satisfactory.

As shown in FIG. 1 the fiber glass case 14 should fit snugly against therear side of ring 16 and snugly over the surface 22a of the samediameter on the projectile and forward edge of the tapered boom.

I claim:

1. A caseless round of ammunition including a projectile having arotating band, a consumable case secured to said projectile, apropellant within said case, and means for guiding said round uponloading thereof into a gun and for providing a shot start effect to saidprojectile, said means including a plastic abutmentring on saidprojectile intermediate said case and rotating band, said ringprojecting laterally of the projectile periphery substantially furtherthan said rotating band.

2. In a caseless round of a fin stabilized projectile having a rotatingband located on said projectile forwardly of the stabilizing fins and apropellant contained consumable case secured to said projectile, thecombination therewith of means for accurately locating said roundlongitudinally in a gun and for providing the projectile with ashot-start effect, said means including an abutment ring on saidprojectile immediate said case and rotating band, said ring extendingradially outward of the projectile pe riphery a substantially greaterdistance than does said rotating band for engaging a rear end portionof'a chamber in a recoilless gun, said ring being of a plastic materialcapable of being sheared when the propellant pressure has reach apredetermined value to increase the starting velocity of said projectileby a shot-start effect.

References Cited by the Examiner UNITED STATES PATENTS BENJAMIN A.BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

1. A CASELESS ROUND OF AMMUNITION INCLUDING A PROJECTILE HAVING AROTATING BAND, A CONSUMABLE CASE SECURED TO SAID PROJECTILE, APROPELLANT WITHIN SAID CASE, AND MEANS FOR GUIDING SAID ROUND UPONLOADING THEREOF INTO A GUN AND FOR PROVIDING A SLOT START EFFECT TO SAIDPROJECTILE, SAID MEANS INCLUDING A PLASTIC ABUTMENT RING ON SAIDPROJECTILE INTERMEDIATE SAID CASE AND ROTATING BAND, SAID RINGPROJECTING LATERALLY OF THE PROJECTILE PERIPHERY SUBSTANTIALLY FURTHERTHAN SAID ROTATING BAND.